[ARM, AArch64] Check the no-stack-arg-probe attribute for dynamic stack probes

This extends the use of this attribute on ARM and AArch64 from
SVN r325900 (where it was only checked for fixed stack
allocations on ARM/AArch64, but for all stack allocations on X86).

This also adds a testcase for the existing use of disabling the
fixed stack probe with the attribute on ARM and AArch64.

Differential Revision: https://reviews.llvm.org/D44291

llvm-svn: 327897

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index dc4185752ea..762da041244 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -13956,6 +13956,20 @@ ARMTargetLowering::LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const
   SDValue Chain = Op.getOperand(0);
   SDValue Size  = Op.getOperand(1);
 
+  if (DAG.getMachineFunction().getFunction().hasFnAttribute(
+          "no-stack-arg-probe")) {
+    unsigned Align = cast<ConstantSDNode>(Op.getOperand(2))->getZExtValue();
+    SDValue SP = DAG.getCopyFromReg(Chain, DL, ARM::SP, MVT::i32);
+    Chain = SP.getValue(1);
+    SP = DAG.getNode(ISD::SUB, DL, MVT::i32, SP, Size);
+    if (Align)
+      SP = DAG.getNode(ISD::AND, DL, MVT::i32, SP.getValue(0),
+                       DAG.getConstant(-(uint64_t)Align, DL, MVT::i32));
+    Chain = DAG.getCopyToReg(Chain, DL, ARM::SP, SP);
+    SDValue Ops[2] = { SP, Chain };
+    return DAG.getMergeValues(Ops, DL);
+  }
+
   SDValue Words = DAG.getNode(ISD::SRL, DL, MVT::i32, Size,
                               DAG.getConstant(2, DL, MVT::i32));